1. Field of the Invention
The present invention relates to heat resistant catalysts, and more particularly to heat resistant and high activity catalysts for use in catalytic reactions such as catalytic combustion, etc., and a method of producing the same.
2. Related Art Statement
Catalysts for catalytic combustion are widely used nowadays for abatement of carbon monoxide and hydrocarbons in exhaust gases from automobiles, for removal of noxious gases in exhaust gases from factories, for deodorization and for non-flame combustion, etc., however, as most of the catalysts have not enough heat resistivity, they are used in special consideration to avoid decrease of the catalyst activity by limiting or controlling operating temperature of the catalyst at a temperature lower than about 800.degree. C. Under these circumstances, development of catalyst of much better heat resistant property has been earnestly desired. Further, catalytic combustions at higher temperature have been of interest in many fields such as gas turbines, boilers and jet engines, and appearance of a remarkably heat resistant and high activity catalyst capable of keeping its high activity even at an extremely high temperature, for example, at a temperature higher than 1,200.degree. C., has been earnestly desired.
In general, a heat resistant catalyst can be produced by supporting catalyst materials on a heat resistant catalyst carrier. In point of this view, the inventors have made extensive studies to develop heat resistant compositions having by far the better heat resistant properties on the basis of an alumina carrier which has the most heat resistant properties among the catalyst carriers being used widely at present, and as the result of this, the inventors showed that the composition consisting mainly of MeO.6Al.sub.2 O.sub.3 (Me being Ca and/or Ba and/or Sr) can be a catalyst carrier having especially superior heat resistant properties, in Japanese patent application No. 60(1985)-189967.
Further, the inventors showed that the above mentioned composition consisting mainly of MeO.6Al.sub.2 O.sub.3 became more heat resistant when it was produced from a complex or mixed alkoxide of aluminum and a metal shown as Me, in Japanese patent application No. 61(1986)140287. In this patent application, the production method of the same are also proposed.